1. Field of the Invention
This invention relates to a useful pharmaceutical composition for the therapy of renal disorder and a dialysis solution for extracorporeal hemodialysis. More particularly, this invention relates to a useful pharmaceutical composition for the therapy of renal disorder and a dialysis solution for extracorporeal hemodialysis each comprising an ascorbyl tocopheryl diester of phosphoric acid or a pharmacologically acceptable salt thereof.
2. Description of the Prior Art
It is known that the active oxygen species and free radicals formed in the body may cause aging and a broad spectrum of diseases inclusive of malignant neoplasms. The kidney, in particular, is highly relevant to such active oxygen species and free radicals because of the vital physiological functions assigned to this organ. In the kidney, literally all toxic substances, drugs and so on are pooled for excretion or reabsorption. As a result, the free radicals formed directly from such substances cause renal disorders. Moreover, a variety of substances including immune complexes in the circulation stimulate the neutrophils and macrophages to release active oxygen species which damage the glomeruli. In addition to kidney disorders due to such blood factors, the role which free radicals play as a causative and exacerbating factor in nephritis through the autoimmune system is attracting attention. In the current drug therapy of nephritis and other disorders of the kidney, various immunosuppressants, drugs having antiplatelet activity, and antiinflammatory drugs are in common use clinically and, in fact, free radical formation inhibitory activity has been discovered in some of these drugs. However, none of them are considered fully satisfactory in terms of the action potential to inhibit free radical formation.
Meanwhile, chronic hemodialysis induces dialysis amyloidosis in the patient on dialysis treatment. As a therapeutic approach, the use of a high-performance dialysis membrane is gaining popularity for eliminating .beta..sub.2 -microglobulin (.beta..sub.2 -MG) which is a causative agent of amyloidosis. However, when this dialysis treatment is performed chronically, symptomatic aggravations are sometimes experienced despite improvements in the .beta..sub.2 -MG picture and it has been pointed out that free radicals are involved in the onset of dialysis amyloidosis as well. However, it is the state of the art that there is not known a dialysis solution for extracorporeal hemodialysis which is effective for the prevention and treatment of amyloidosis.
Under the circumstances, a real demand exists in the art for a drug and a hemodialysis solution which would successfully inhibit the formation of, or scavenge, free radicals in vivo and, as such, be useful for the prophylaxis and therapy of various disorders of the kidney.
The inventors of this invention long studying the pharmacological actions of ascorbyl tocopheryl diester of phosphoric acid discovered that this compound effectively inhibits the formation of free radicals in the body and scavenges them and is of value as a therapeutic drug for renal disorder or a dialysis solution for extracorporeal hemodialysis. This invention has been developed on the basis of the above findings.